高糖对大鼠心肌细胞NMDA受体表达、胞内钙和超氧自由基水平的影响

目的 探讨高浓度葡萄糖对心肌细胞促离子型谷氨酸受体亚型NMDA受体（NMDAR）表达、胞内钙水平以及活性氧自由基产生的影响.方法 分离新生（1～3天）大鼠心室肌细胞,心肌细胞与不同浓度葡萄糖（对照组葡萄糖浓度5mmol/L,高糖组葡萄糖浓度33mmol/L）共孵育24 ～ 72h后,用Western blot法检测心室肌细胞NMDAR1和NMDAR2B亚单位的表达水平,活细胞工作站检测胞内Ca2＋水平,流式细胞术检测细胞内活性氧自由基（ROS）含量.结果 与对照组细胞相比,高浓度葡萄糖使心肌细胞的NMDAR2B的表达水平明显上调（P＜0.05）,而NMDAR1的表达则降低.经高糖处理的心肌细胞在收缩时胞内钙水平高于对照细胞,高糖处理使心肌细胞的ROS水平升高,而用MK-801选择性阻断NMDAR可明显降低由高糖所致的胞内ROS增高（与高糖组对比,P ＜0.05）.结论 高浓度葡萄糖可上调乳鼠心肌细胞NMDAR2B及下调NMDAR1的表达,并增加细胞内Ca2＋水平及ROS的生成,而阻断NMDAR可抑制ROS的生成.提示NMDAR可能参与糖尿病性心肌损害。

Effects of High Glucose on NMDA Receptor Expression,Intracellular Ca2 + and ROS Levels in Cultured Neonatal Rat Cardiomyocytes

Objective To investigate the effects of high glucose on NMDA receptor （NMDAR） expression, intracellular calcium and reactive oxygen species （ROS） levels in cardiomyocytes. Methods Hearts were harvested from neonatal SI） rats and ventricular myocytes were isolated and cultured. Western blot was used to investigate the expressions of NMDAR, confocal microscopy was to determine the intracellular Ca2＋ level, flow cytometry to examine the production of intracellular reactive oxygen species （ ROS）. Results Compared with the control cells （ treated with 5mmol/L glucose）, incubation of cardiomyocytes with high glucose （33mmol/L） for 72h increased the protein expression of NMDAR2B, but decreased the protein level of NMDAR1 （both P 〈 0.05 ）. High glucose also elevated the intracellular Ca2＋ and ROS levels in cardiomyocytes. Selective blockade of NMDAR by MK- 801 （30μmol/L） suppressed the elevation of ROS induced by high glucose. Conclusion High glucose upregulates NMDAR2B expression but downregulates NMDAR1 expression, enhances calcium mobilization and ROS production in cultured neonatal rat cardiomyocytes. Blocking NMDAR suppressed the ROS production induced by high glucose. These results suggested that NMDAR may be a pharmacological target for treating diabetic cardiomyopathy.